Method for transferring a large number of fiber ends into a specified position

ABSTRACT

A method for transferring a large number of fiber ends of a bundle of light wave guides, especially glass, quartz or plastic fibers, into a large number of specified positions with the aid of an alignment apparatus which includes openings the size of which can be varied in a specified range. The method includes passing the glass, quartz or plastic fiber ends through the openings of the alignment apparatus, whereby the size of the openings are selected such that only one end of the large number of glass, quartz or plastic fiber ends can pass through each opening. The size of the openings is then reduced so that the glass, quartz or plastic fiber ends are moved to the specified positions.

BACKGROUND

[0001] The invention concerns a method for transferring a large numberof fiber ends of a bundle of optical waveguides, especially glass,quartz or plastic fibers, into a large number of specified positionswith an alignment apparatus which includes openings which vary in sizein a specified range as well as a method for manufacturing a glass,quartz or plastic fiber ends which are connectable with a plugarrangement.

[0002] With glass fiber cables with a great number of glass fibers, ithas up until now been customary to grasp the individual fibers manuallyand transfer them individually into a specified position.

[0003] In this way, for example, glass fibers could be arranged lyingalongside one another, in a one dimensional array, and joined togetherto form a plug connector for a glass fiber cable.

[0004] The disadvantage in a process of this type was that this processis very expensive for an exact positioning of many glass, quartz andplastic fiber ends.

[0005] In particular, a process of this type does not permittransferring a two-dimensional glass fiber array with, for example, 2×2to 40×40 glass fibers, into a connector so that a glass fiber cable witha large number of glass fibers in a two dimensional, for example squareor rectangular matrix results. In particular, the WO processes accordingto the state of the art did not allow a very exact positioning, in therange of a few micrometers (μm), of a large number of closely spacedglass fiber ends.

SUMMARY

[0006] Consequently, it is the object of the invention to provide amethod with which these disadvantages can be overcome, especially toprovide a method which makes possible a very exact positioning in a twodimensional matrix with a spacing between the fiber ends of a few μm. Inparticular, in this way, a simplified point-to-point arrangement of twoglass fiber ends is made possible. Furthermore, the procedure shouldpermit an extensive automation in connection with the manufacture ofglass fiber cables.

[0007] In accordance with the invention, this is achieved in that thefiber ends are passed through the openings of an alignment apparatus, inwhich the size of the openings have been selected such that at most onefiber end of a glass fiber, preferably without a protective layer, canpass through an opening. In a second step, the size of the openings arereduced so that the fiber ends arrive at the specified positions.

[0008] The advantage of a solution of this type is especially that theindividual fibers can be transferred into positions lying very closealongside one another since with such a process very close distances,as, for example, are specified by the bar widths of an alignmentapparatus, no problems arise in connection with positioning.

[0009] With such a method, glass fiber ends can be brought exactly-intoa position up to <±2 μm, whereby the individual glass fibers with core,cladding and protective coating can have a diameter of from 20 μm andpreferably 100 μm to 1000 μm, and most preferably 260 μm. The strippedglass fiber ends without protective coating include a core and claddingand can have a diameter in the 50 to 800 μm range.

[0010] One configuration for the alignment apparatus is constructed inthe form of a perforated plate, whereby the individual openings areformed by bars. In a first position, the size of the opening is selectedsuch that at most a stripped glass fiber end without protective coatingcan pass through. This provides, in comparison to a perforated platehaving fixed distance openings, a relatively large-meshed net. The barsare slidable to a second position, in which they define a fine-meshednet where each position of the individual openings corresponds to thedesired position of the glass fiber end in a glass fiber array.

[0011] Preferably, distance between bars is selected to be <105 μm inthe first position and <95 μm in a second position. The diameter of theindividual bars corresponds to the standard distance between theindividual glass fibers in the desired glass fiber matrix.

[0012] The alignment apparatus of the invention with flexiblematrix-permits, first of all, the individual fibers to be able to beintroduced into a relatively broad opening, the size of which must beselected so that in the first position, the entry of a second fiber isprevented. The opening size for exact positioning of the individualfibers is then selected such that the spacing between the barscorresponds to the diameter of the glass fiber ends.

[0013] A solution of this type has, for example, in comparison with afixed matrix, the advantage that it can almost be ruled out thatindividual fibers do not extend through the holes and must berepositioned in an expensive repair process in the traditional manner.

[0014] A further advantage is that the fibers can at the same time beguided by several alignment apparatuses, whereby the size of theopenings of each individual alignment device is individually adjustable.

[0015] Passing the fiber ends through the coarse-meshed net is assistedby the glass fiber ends and/or the alignment apparatus beingperiodically moved, especially set into vibration. This can take placeby shaking.

[0016] In addition to the method of the invention for positioning, theinvention also provides a method for manufacturing glass fiber ends toform a plug connection which includes a large number of individual glassfibers.

[0017] Only with an assembly technique of this type is it possible tomake available a glass fiber cable at a reasonable manufacturing expensewith a two dimensional glass fiber array which can be used, for example,in the area of optical data communication.

[0018] A process of this type for manufacturing glass fiber ends whichcan be used to form a plug connection includes the step of positioningthe individual glass fibers with the aid of the method of the invention,into a preliminary alignment of the fiber ends and then into a finalfixed arrangement. The final fixed arrangement of the fiber ends can,for example, be attained by filling the spaces between the fiber endswith a casting or potting material and subsequent hardening. This finalfixed arrangement can, for example, be incorporated into a plugconnector.

[0019] After introducing such an end of a glass fiber cable with glassfibers which are arranged in a two dimensional matrix into a plugarrangement, it is necessary for a sufficient optical qualityconnection, for the glass fiber ends of the glass fibers to be groundand polished so that the glass fiber array defines a smooth plane.

[0020] For a sufficiently good positioning in a glass fiber array, it isnecessary for the glass fiber ends to be individual glass fibers withoutany protective coating. That is, the glass fiber ends are merelycomprised by the glass fiber core and the glass cladding.

[0021] Preferably plastic and/or an adhesive are used as casting orpotting material.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The invention is to be described below on the basis of thepreferred embodiments. Although the preferred embodiments relate toglass fibers as optical waveguides, the method of the invention can alsobe used on other optical wave guides, such as, for example, quartz orplastic fibers, without deviating from the invention.

[0023] In the drawings:

[0024]FIG. 1 is a side elevational view of a preferred construction forimplementing the method of the invention whereby the passage of theglass fiber ends through the openings of the alignment device isassisted by motion,

[0025]FIG. 2A is a plan view of the alignment apparatus with spacerswhich in the closed state guarantee a defined distance, whereby the barsare situated in a first position, to produce a coarse-meshed net,

[0026]FIG. 2B is a plan view of the alignment apparatus of FIG. 2A withspacers, whereby the bars are in the second position, producin thefine-meshed net, and

[0027]FIG. 3 is a perspective view of a glass fiber cable manufacturedusing the method of the invention with a large number of glass fibersarranged in a two dimensional matrix.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028]FIG. 1 shows a preferred structure for positioning a large numberof glass fiber elements with the aid of an alignment apparatus 3 withvariable openings.

[0029] Clearly recognizable is the great number of glass fiber ends 1 ofthe glass fiber cable. Each individual glass fiber of the glass fibercable is formed of a glass fiber core, a cladding or cladding glass, aswell as a protective layer which surrounds the cladding or claddingglass.

[0030] For positioning the individual glass fiber ends 1 the glassfibers in accordance with the method of the invention, the protectivelayer is removed from the individual glass fibers in the region of thefiber ends 1. The individual glass fiber ends 1 are transferred to analignment apparatus 3 which is constructed generally in the form of aperforated plate formed from individual bars, whereby the bars of theinvention can be moved to provide a variable bar distance so thatopenings with various opening diameters are formed.

[0031] The opening size is so dimensioned in a first position thatpreferably at most one fiber end, including core and cladding, but notthe protective layer, can pass through the opening. The perforated plateis a relatively coarse-meshed matrix in this position.

[0032] If now the bundle 5 of fiber ends 1 is placed on the perforatedplate 3, then the individual glass fiber ends 1 pass through theopenings and are roughly positioned.

[0033] Due to the large openings, 100% of the stripped fiber ends fallthrough the openings and can thus be prepositioned.

[0034] Should all the holes not be filled and individual fibers of thegreat number of glass fibers not pass through the perforated screen,these individual fibers can be manually reprocessed.

[0035] To come from the very crude positioning to the very closelytoleranced array, the individual wires which form the bars can be pushedtogether. The tolerance of the individual positions lies in thetelescoped array in the ±0.5 μm to +2 μm range. In order to obtain lowtolerances of this sort, the individual bars are kept at a distance byspacers in the pushed-together position.

[0036] After the individual glass fibers have been transferred into thespecified positions through the fine-meshed matrix and there temporarilyaligned, the glass fiber ends present in an ordered matrix are affixedin the aligned position, for example by means of a casting material orpotting material. Preferably, the fiber ends are coated with aplastic/adhesive that is subsequently hardened. In this way, a fixedalignment of the fiber ends in the desired position is attained.

[0037] Subsequently, the cable end produced in this way can be groundand polished true so that a planar fiber array is obtained. The roughpositioning of the glass fiber ends can be assisted by moving orvibrating the alignment apparatus and/or the glass fiber ends.

[0038] A preferred configuration of the flexible alignment device of theinvention which is configured as a matrix is represented in FIGS. 2A and2B.

[0039] The flexible matrix includes a supporting frame 9, a system ofcross bars 10, 12 which define a large number of openings 14 in thematrix structure. The distance between the bars is set such that theinsertion of a second fiber through any of the openings is prevented.The diameter of the individual bars corresponds to the standard distancebetween the individual glass fibers in the array to be produced wherebythe bar widths are advantageously smaller than the diameters of theglass fiber ends.

[0040] As represented in FIG. 2A, the bars in this first position form arelatively coarse-meshed net.

[0041] After the individual fibers have been transferred into the largeopenings 14 of the coarse-meshed net of the flexible matrix, the rodsare moved in the direction of arrow 16 to stop 18 and spaced apart by aset distance by spacers 19. In the fine meshed net represented in FIG.2B, the individual glass fiber ends 1 are tightly packed into a matrixand are spaced apart by a distance which corresponds to the bar width ofthe individual bars 10, 12, whereby the diameter of the bars ispreferably smaller than the diameter of an individual glass fiber end.

[0042] In FIG. 3, a glass fiber cable 100 which was manufacturedaccording to the method of the invention is represented. The glass fibercable 100 includes a large number of glass fiber ends 1 which arearranged in an array. The size of the array can, for example, be 10×10or 35×35, or any other desired size, and can also be a non-square,rectilinear glass fiber array with, for example, 16×32 glass fibers. Thedistance d of the individual fiber cores to one another comes to 125 μmin the present embodiment, the tolerance in the placement deviation is±3 μm. The individual glass fibers are preferably formed of a glassfiber core with a diameter in the 50 μm range, a cladding, whichsurrounds the glass fiber core, as well as a protective coating. Onepreferred glass fiber with protective layer has a diameter ofapproximately 110 to 120 μm. Of course, arrays with other arrangementsor with glass fibers with a different dimensioning are also possiblewithout deviating from the invention.

[0043] Preferably, a casing 110 surrounds the large number of fibers.

[0044] Quartz, other types of glass or a plastic material can be used asglass fiber material. The glass fiber surface includes an acrylatecoating. Multi-modal as well as single mode fibers can be used.

[0045] A complete glass fiber cable results when a plug connection isplaced at both ends of the array of glass fibers.

[0046] With the method of the invention, it is possible for the firsttime to manufacture a glass fiber cable which includes amulti-dimensional matrix of individual glass, quartz or plastic fibersin an ordered arrangement. The advantage of the method in particularlies in that it is herewith possible for the first time to create aglass, quartz or plastic fiber array where the distance between theindividual glass, quartz or plastic fibers is smaller than the diameterof the individual fibers, whereby the positioning within the array hastolerances in the range of ±2-±0.5 μm.

What is claimed is:
 1. A method for transferring a plurality of fiberends of a bundle of optical wave guides into a plurality of specifiedpositions, comprising: (a) providing an alignment apparatus whichincludes openings having sizes which can be varied in a specified range;(b) selecting a first opening size such that only one end of theplurality of fiber ends can pass through the opening; (c) passing thefiber ends through the openings of the alignment apparatus; (d) reducingthe size of the openings to a second, reduced opening size so that theplurality of fiber ends are moved into the specified positions. 2.Method according to claim 1, wherein the aligning device includes atleast one flexible matrix with openings in the form of a perforatedplate.
 3. Method according to claim 2, wherein the flexible matrix iscomprised of moveable bars, the method further including adjusting adistance between the bars to place the bars in a first position todefine the openings with the first opening size such that at most onefiber end without a protective coating can be inserted, and afterpassing the fiber ends through the openings, adjusting the distancebetween the bars to place the bars in a second position whichcorresponds to the second opening size so that the distance between thebars corresponds to a diameter of the fiber ends.
 4. Method according toclaim 3, wherein the distance between bars in the first position isabout 105 μm, and the distance between the bars in the second positionis <95 μm.
 5. Method according to claim 1, further comprising moving orvibrating at least one of the fiber ends and the alignment apparatus. 6.Method of claim 1, wherein the fiber ends are at least one of glass,quartz and plastic.
 7. Method for manufacturing an end of a fiber cablehaving a plurality of individual fiber ends into a plug connection,comprising: (a) providing an alignment apparatus which includes openingshaving sizes which can be varied in a specified range; (b) selecting afirst opening size such that only one end of the plurality of fiber endscan pass through the opening; (c) passing the fiber ends through theopenings of the alignment apparatus; (d) reducing the size of theopenings to a second, reduced opening size so that the plurality offiber ends are moved into the specified positions; (e) temporarilyholding the fiber ends in the specified positions with the alignemntapparatus; and (f) fixing the fiber ends in the specified positions. 8.Method according to claim 7, wherein the fixing of the fiber endscomprises casting with at least one of a casting, potting and adhesivematerial around the fiber ends to at least partially fill spaces betweenthe fiber ends, and subsequent hardening of the casting material. 9.Method according to claim 8, wherein the fiber ends are formed fromfibers from which a protective coating is removed.
 10. Method accordingto claim 9, wherein the protective coating of the fibers comprises lessthan 50% of an overall diameter of the fibers.
 11. Method according toclaim 7, wherein the fiber ends are ground and polished, resulting in afiber array.
 12. Method of claim 7, wherein the fiber ends are glass,quartz or plastic.